Multiple types of switchable valve train systems including rocker arms arranged on rocker shafts are known. One type of switchable valve train system includes rocker arms with a hydraulic lash adjuster and a locking assembly arranged on opposite sides of the rocker arm. One type of known rocker shaft includes a hollow center for directing hydraulic fluid from a feed port to the hydraulic lash adjuster and the locking assembly of an associated rocker arm.
One known arrangement of a switchable valve train is shown in FIG. 1, which is from U.S. Pub. 2008/0302322. As shown in FIG. 1, the switchable valve train assembly 100 includes a rocker shaft 101 having a plurality of intake ports 102. A plurality of switchable rocker arm assemblies 110 are provided along the rocker shaft 101 that include a camshaft end 106 and a valve end 108. The rocker shaft 101 includes a hollow center 104 for directing hydraulic fluid from a hydraulic fluid supply assembly (not shown) to the associated switchable rocker arm assemblies 110. The switchable rocker arm assemblies 110 are selectively controlled to actuate a locking assembly and to supply pressurized hydraulic fluid to the lash adjuster (not shown) associated with each switchable rocker arm assembly 110 based on a supply of hydraulic fluid from the hollow center 104 of the rocker shaft 101. The flow of hydraulic fluid through the rocker shaft 101 can create air bubbles or pockets, which causes hydraulic fluid flow fluctuations and disrupts performance of the rocker arm assemblies. The switchable valve train assembly 100 also includes two standard rocker arms 105 outside of the switchable rocker arm assemblies 110.
It would be desirable to provide a rocker shaft that offers a reliable, continuous flow of de-aerated hydraulic fluid from the hydraulic fluid supply assembly to the locking assembly of the rocker arm assembly.